An Overview of CNC

CNC Definition

CNC stands for Computerized Numerical Control. It is a computerized manufacturing process in which pre-programmed software and code controls the movement of production equipment.

CNC Machining Definition

CNC machining controls a range of complex machinery, such as grinders, lathes, and turning mills, all of which are used to cut, shape, and create different parts and prototypes.

CNC Machining Process Basics

Evolving from the numerical control (NC) machining process which utilized punched tape cards, CNC machining is a manufacturing process which utilizes computerized controls to operate and manipulate machine and cutting tools to shape stock material—e.g., metal, plastic, wood, foam, composite, etc.—into custom parts and designs. While the CNC machining process offers various capabilities and operations, the fundamental principles of the process remain largely the same throughout all of them. The basic CNC machining process includes the following stages:

  • Designing the CAD model
  • Converting the CAD file to a CNC program
  • Preparing the CNC machine
  • Executing the machining operation

CNC Machining Materials

The CNC machining process is suitable for a variety of engineering materials, including:

  • Metal (e.g., aluminum, brass, stainless steel, alloy steel, etc.)
  • Plastic (e.g., PEEK, PTFE, nylon, etc.)
  • Wood
  • Foam
  • Composites

The optimal material for selection to apply to a CNC manufacturing application is largely dependent on the particular manufacturing application and its specifications. Most materials can be machined provided that they can withstand the machining process—i.e., have sufficient hardness, tensile strength, shear strength, and chemical and temperature resistance.

The workpiece material and its physical properties are used to determine the optimal cutting speed, cutting feed rate, and depth of cut. Measured in surface feet per minute, the cutting speed refers to how fast the machine tool cuts into or removes material from the workpiece. The feed rate—measured in inches per minute—is a measure of how fast the workpiece is fed towards the machine tool, and the cut depth is how deep the cutting tool cuts into the workpiece. Typically, the workpiece will first undergo an initial phase in which it is roughly machined to the approximate, custom-designed shape and dimensions, and then undertake a finishing phase in which it experiences slower feed rates and shallower cut depths to achieve its more precise and accurate specifications.

Test Yourself


Concerning Reality (2018). What is CNC machining and how does it work? [Video]. YouTube.

Goodwin University (2018). What is CNC? Retrieved on July 24, 2023 from

Hubs (2020). CNC machining – what is it and how does it work? [Video]. YouTube.

Staff (2023). What is CNC machining? Thomas. Retrieved on July 24, 2023 from


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ETD 433 by Jarred Finnerman and Andrea Bearman is licensed under a Creative Commons Attribution 4.0 International License, except where otherwise noted.

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